Adapting Read Thresholds for Analog Memory Pages
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Solution Overview
Problem
Existing memory devices face challenges in efficiently reading data from analog memory cells due to variations in optimal read threshold values across different pages, leading to increased readout time and error probabilities.
Innovation Solution
A method and system for storing and adapting read thresholds, where multiple sets of read thresholds are associated with each erasure block, allowing for the retrieval and adaptation of thresholds from one page to match another within the same block, reducing the need for trial-and-error and improving readout efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sets of read thresholds are stored for each page in an erasure block, then reading accuracy is improved, but memory resource consumption increases
Solution Approach 1:
The patent pre-calculates and stores read threshold values for representative pages during manufacturing or initialization. When a read operation is needed, the system retrieves pre-computed thresholds for the target page or adapts thresholds from similar pages, avoiding the need to compute thresholds in real-time and reducing the need to store separate threshold sets for every possible page condition.
Solution Approach 2:
The system adapts read thresholds by adjusting parameters based on page characteristics such as position within the erasure block, wear level, or data pattern. Instead of storing completely separate threshold sets for each page, the system stores base thresholds and applies parameter adjustments to generate page-specific thresholds, significantly reducing memory requirements while maintaining reading accuracy.
2Measurement precision
If trial-and-error methods are used to determine optimal read thresholds, then reading accuracy can be achieved, but readout time increases
Solution Approach 1:
Optimal read threshold values are pre-determined and stored for each page or page group during manufacturing or initialization. When a read operation is performed, the system directly retrieves the pre-computed thresholds for the target page, eliminating the need for time-consuming trial-and-error adjustments during actual read operations.
Solution Approach 2:
The system copies or adapts read threshold values from representative pages or neighboring pages within the same erasure block. Instead of performing trial-and-error searches for each page, the system copies thresholds from similar pages and makes minimal adjustments, dramatically reducing readout time while maintaining accuracy.
3Reliability
If page-specific read thresholds are stored for every page, then reading reliability is improved, but device complexity increases
Solution Approach 1:
The patent segments the erasure block into groups of pages that share similar characteristics (e.g., position, wear level, data pattern). Instead of managing completely independent threshold sets for each individual page, the system manages threshold sets for page groups, reducing complexity while maintaining reliability through group-specific optimization.
Solution Approach 2:
The system implements a universal threshold management mechanism that can serve multiple pages through adaptation. A single base threshold set or a small number of representative threshold sets can be adapted to serve multiple pages within an erasure block, reducing the overall number of threshold sets needed while maintaining reading reliability across all pages.
Data Source
AI summary
A method for data storage includes storing multiple sets each including one or more read thresholds for use in reading data from a plurality of analog memory cells. The memory cells are arranged in multiple erasure blocks each including multiple pages, and each set of read thresholds is associated with a respective page in one of the erasure blocks. A first page, which belongs to a given erasure block and is not associated with any of the stored sets of read thresholds, is read by retrieving a stored set of read thresholds that is associated with a second page in the given erasure block, adapting the retrieved set of read thresholds to match the first page, and reading the first page using the adapted set of read thresholds.